Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add kok-o/koko-contextos-agents --skill performancegit clone --depth 1 https://github.com/kok-o/koko-contextos-agentsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/kok-o/koko-contextos-agents/performance)<a href="https://agentmods.dev/skills/kok-o/koko-contextos-agents/performance"><img src="https://agentmods.dev/badge/skills/kok-o/koko-contextos-agents/performance/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/kok-o/koko-contextos-agents/performance"><img src="https://agentmods.dev/badge/skills/kok-o/koko-contextos-agents/performance.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00026 | $0.00950 |
| Opus 5.5 | $0.00010 | $0.00380 |
| Sonnet 5.5 | $0.00005 | $0.00190 |
| Haiku 4.5 | $0.00003 | $0.00095 |
Grade A, and why
Web Performance scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 76 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Web Performance & Core Web Vitals
Overview
Enforces high-efficiency frontend and full-stack performance standards to achieve exceptional Core Web Vitals: Largest Contentful Paint (LCP < 2.5s), Interaction to Next Paint (INP < 200ms), and Cumulative Layout Shift (CLS < 0.1).
When to Use
Activate whenever analyzing, profiling, writing, or optimizing page loading speeds, network waterfalls, script bundling, animation frame rates, or data caching.
Negative Constraints (What NOT to Do)
- NEVER introduce async waterfalls: Do not chain sequential
awaitcalls when requests can be executed concurrently viaPromise.all(). - NEVER import large full libraries when only a utility is needed: Never
import _ from 'lodash'; useimport debounce from 'lodash/debounce'or native alternatives. - NEVER render images or videos without explicit aspect ratios: Always provide
widthandheightoraspect-ratioto avoid Cumulative Layout Shift (CLS). - NEVER trigger synchronous layout thrashing: Do not alternate between reading layout properties (
offsetHeight,getBoundingClientRect) and writing styles in loops. - NEVER animate non-composited properties: Animate only GPU-composited CSS properties (
transform,opacity). Never animatewidth,height,top,left, ormargin.
Rules & Patterns
1. Vercel Optimization Hierarchy by Impact
| Priority | Category | Key Optimization Target | Expected Impact |
|---|---|---|---|
| 1. CRITICAL | Eliminating Waterfalls | Parallel data fetching (Promise.all), Suspense streaming |
30–60% faster LCP |
| 2. CRITICAL | Bundle Size Optimization | Direct submodule imports, next/dynamic, deferring 3rd party scripts |
40–70% smaller initial JS |
| 3. HIGH | Server-Side & RSC Caching | React.cache() request deduplication, edge SSR caching |
Lower TTFB & DB load |
| 4. MEDIUM-HIGH | Client Query Optimization | SWR / TanStack Query stale-while-revalidate, deduplication | Zero redundant network calls |
| 5. MEDIUM | Render & DOM Optimization | Virtualization for large lists, state colocation, :focus-visible |
Smooth 60 FPS / INP < 100ms |
What ships with it
5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 76 lines · 26 tokens per session scan A 8ce77d672073
Web Performance is a skill published in the GitHub repository kok-o/koko-contextos-agents (2 stars, last pushed 1mo ago), licensed MIT. It adds 26 tokens to every session and 950 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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